first quarter of 2017, United entered into a CPA amendment with
 Mesa Air Group, Inc. (“Mesa Air Group”) and Mesa
 Airlines, Inc. (“Mesa”), a wholly-owned subsidiary of
 Mesa Air Group, for Mesa to operate these 12 additional Embraer
 E175 aircraft under the United Express brand. As of
 December 31, 2016, all 12 of these aircraft are expected to be
 delivered in 2017.
In 2015, United entered
 into amendments to the CPA with SkyWest Airlines, Inc.
 (“SkyWest”), a wholly-owned subsidiary of SkyWest,
 Inc., to operate an additional 25 new 76-seat Embraer E175 aircraft under
 the United Express brand. SkyWest purchased all of these
 76-seat aircraft directly
 from the manufacturer with seven deliveries remaining in
 2017.
In 2015, United entered
 into a new CPA with Champlain Enterprises, LLC d/b/a CommutAir
 (“CommutAir”), pursuant to which CommutAir will operate
 40 used Embraer ERJ145 aircraft under the United Express brand that
 are currently being operated by a different United Express regional
 carrier, with transfers that are continuing through 2018. As of
 December 31, 2016, 28 aircraft are still pending
 transfer.
Our future commitments
 under our CPAs are dependent on numerous variables, and are
 therefore difficult to predict. The most important of these
 variables is the number of scheduled block hours. Although we
 are not required to purchase a minimum number of block hours under
 certain of our CPAs, we have set forth below estimates of our
 future payments under the CPAs based on our
 assumptions. United’s estimates of its future payments
 under all of the CPAs do not include the portion of the underlying